Add unit tests for Config.java.

[cfb.git] / prod / net / jaekl / qd / util / FileIO.java

diff --git a/prod/net/jaekl/qd/util/FileIO.java b/prod/net/jaekl/qd/util/FileIO.java
new file mode 100644 (file)
index 0000000..450d6ed
--- /dev/null
+++ b/prod/net/jaekl/qd/util/FileIO.java
@@ -0,0 +1,42 @@
+package net.jaekl.qd.util;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+// Dispatch File Input/Output operations from a singleton
+// This makes it possible to intercept file reads and writes
+// during unit testing, and replace them with mock operations.
+
+public class FileIO {
+       // Note:  need volatile to implement double-checked locking in getInst()
+       static volatile FileIO m_inst = null;
+       
+       FileIO() { ; }
+       
+       public static FileIO getInst() { 
+               FileIO result = m_inst;
+               if (null == result) {
+                       synchronized(FileIO.class) {
+                               if (null == m_inst) {
+                                       m_inst = new FileIO();
+                               }
+                               result = m_inst;
+                       }
+               }
+               return result;
+       }
+       
+       public InputStream openInput(File file) throws FileNotFoundException 
+       {
+               return new FileInputStream(file);
+       }
+       
+       public OutputStream openOutput(File file) throws FileNotFoundException 
+       {
+               return new FileOutputStream(file);
+       }
+}